Adaptive buck-boost drive circuit, drive method and vehicle lamp

Abstract

The present invention belongs to the technical field of electronic circuits, and particularly relates to an adaptive buck-boost drive circuit, a drive method, and an automotive lamp. The adaptive buck-boost drive circuit includes a main control, a Boost circuit, and a load. The positive electrode of the load is connected to the positive output terminal of the Boost circuit. The adaptive buck-boost drive circuit further includes: a first switching transistor, whose drain is connected to the negative electrode of the load, source is grounded, and gate is connected to the main control; a first diode, whose positive electrode is connected to the drain of the first switching transistor, and negative electrode is connected to the power supply terminal of the Boost circuit. The present invention can automatically switch the circuit to a boost state or a buck-boost state according to the connected load condition, fully utilize the boost characteristic of the Boost circuit, optimize the power efficiency, and eliminate the need to confirm the load connection condition during wiring, thus simplifying the wiring method for workers and improving the yield rate.

Description

Technical Field

[0001] The present invention belongs to the technical field of electronic circuits, and particularly relates to an adaptive buck-boost drive circuit, a drive method and an automobile lamp. Background Art

[0002] Automobile headlight drive boards generally use a voltage of about 12V for power supply. However, since different automobile headlights use different numbers of LED strings, the voltage for driving one string of LEDs is about 3V. If the number of LED strings in the automobile headlight is less than 4 strings, the total voltage for driving the LEDs is less than 12V, then the automobile headlight drive board needs to step down the voltage to drive the LEDs; if the number of LED strings in the automobile headlight is greater than 4 strings, the total voltage for driving the LEDs is greater than 12V, then the automobile headlight drive board needs to step up the voltage to drive the LEDs. That is to say, the automobile headlight drive board needs to implement the buck-boost function to drive LEDs with different numbers of strings.

[0003] There are currently two solutions. One is to use a 4-switch Buck-Boost circuit to implement the buck-boost function. The reference application circuit is as Figure 1 shown. The advantage of this circuit is that the buck-boost function can be achieved by controlling the switching states of 4 switching tubes, so as to drive LEDs with different numbers of strings. However, the disadvantages of this circuit are also obvious. It uses 4 MOS tubes, with high cost, complex control, and poor reliability of this bridge architecture. Once the upper and lower tubes are short-circuited, the problem of burning the MOS tubes will occur. Another most commonly used solution is to use a Boost circuit to implement the buck-boost function, and let the Boost circuit work in the buck-boost state. The reference application circuit is as Figure 2 shown. Connect the LED- back to the positive pole of the input power supply. The reason for doing this is that the Boost circuit can only step up the voltage. Connecting the LED- back to the positive pole of the input power supply, so that the actual output voltage is equal to the voltage dropped on the total LEDs plus the voltage of the input power supply, that is, the output voltage must be greater than the input voltage, ensuring that the Boost circuit can work properly. Figure 2 The current path flowing through the LED is also marked in Figure 2 . In Figure 2Connect the wires in the way of LED+ and LED-; if it is confirmed that the number of LED lamp beads in series is more than 6, the wiring worker will connect LED+ to the Figure 2 position shown, but will directly ground LED-. This results in Figure 2 There is also a problem with the application solution of SUMMARY OF THE INVENTION

[0004] In view of the technical problem that when using a Boost circuit to realize the step-up and step-down functions in the prior art, manual wiring needs to be carried out according to the load situation, resulting in complex manual wiring and easy to make mistakes, the purpose of the present invention is to provide an adaptive step-up and step-down drive circuit, a drive method and an automotive lamp.

[0005] To solve the foregoing technical problem, a first aspect of the present invention provides an adaptive step-up and step-down drive circuit, the adaptive step-up and step-down drive circuit includes a main control, a Boost circuit and a load, and the positive pole of the load is connected to the positive output terminal of the Boost circuit;

[0006] The adaptive step-up and step-down drive circuit further includes:

[0007] A first switching tube, the drain of the first switching tube is connected to the negative pole of the load, the source of the first switching tube is grounded, and the gate of the first switching tube is connected to the main control;

[0008] A first diode, the positive pole of the first diode is connected to the drain of the first switching tube, and the negative pole of the first diode is connected to the power supply terminal of the Boost circuit.

[0009] Optionally, in the adaptive step-up and step-down drive circuit as described above, the first switching tube is an NMOS tube.

[0010] Optionally, in the adaptive step-up and step-down drive circuit as described above, the first switching tube is an enhanced NMOS tube.

[0011] Optionally, in the adaptive step-up and step-down drive circuit as described above, the load is an LED lamp.

[0012] Optionally, in the adaptive step-up and step-down drive circuit as described above, the adaptive step-up and step-down drive circuit further includes:

[0013] A voltage acquisition circuit, the voltage acquisition circuit is configured to acquire the voltage at the positive terminal of the load, and the output terminal of the voltage acquisition circuit is connected to the main control.

[0014] Optionally, in the adaptive step-up and step-down drive circuit as described above, the Boost circuit includes:

[0015] Energy storage inductor, one end of the energy storage inductor is connected to the power supply terminal;

[0016] Second diode, the negative electrode of the second diode is connected to the positive electrode of the load;

[0017] Filter capacitor, the positive electrode of the filter capacitor is connected to the negative electrode of the second diode, and the negative electrode of the filter capacitor is grounded;

[0018] Second switching tube, the drain of the second switching tube is respectively connected to the other end of the energy storage inductor and the positive electrode of the second diode, the source of the second switching tube is grounded, and the gate of the second switching tube is connected to the main control.

[0019] To solve the foregoing technical problems, the second aspect of the present invention provides an adaptive buck-boost driving method for driving the adaptive buck-boost driving circuit provided in the first aspect of the present invention. The adaptive buck-boost driving method includes:

[0020] After power-on, the main control controls the first switching tube to turn off, so that the adaptive buck-boost driving circuit operates in the buck-boost state;

[0021] The main control collects the voltage value at the positive terminal of the load. If the voltage value is greater than the preset value, it controls the first switching tube to conduct, so that the adaptive buck-boost driving circuit operates in the boost state. If the voltage value is not greater than the preset value, it keeps the first switching tube in the off state.

[0022] Optionally, in the adaptive buck-boost driving method as described above, the preset value is:

[0023] 2Vin + N

[0024] Wherein, Vin is the voltage input at the power supply terminal of the Boost circuit, and N is a preset driving switching voltage value.

[0025] Optionally, in the adaptive buck-boost driving method as described above, when the load is an LED lamp, N≥6V.

[0026] To solve the foregoing technical problems, the third aspect of the present invention provides an automotive lamp, and the automotive lamp has the adaptive buck-boost driving circuit provided in the first aspect of the present invention.

[0027] The positive and progressive effects of the present invention are: Compared with traditional solutions such as Figure 2Compared with the Boost circuit that can only work in the buck-boost state, the present invention can automatically switch the circuit to the boost state or the buck-boost state according to the connected load conditions, giving full play to the boost characteristics of the Boost circuit, optimizing the power efficiency, and eliminating the need to confirm the load connection when wiring, simplifying the wiring method for workers and improving the yield rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] With reference to the accompanying drawings, the disclosure of the present invention will become more apparent. It should be understood that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. In the figures:

[0029] Figure 1 FIG. is a circuit schematic diagram of a buck-boost circuit using a 4-switch in the prior art to achieve buck-boost function;

[0030] Figure 2 FIG. is a circuit schematic diagram of a buck-boost circuit using a Boost circuit in the prior art;

[0031] Figure 3 FIG. is a basic circuit schematic diagram of a Boost circuit in the prior art;

[0032] Figure 4 FIG. is a circuit schematic diagram of the present invention;

[0033] Figure 5 FIG. is another circuit schematic diagram of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0035] It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0036] In the description of the present invention, it should be noted that for orientation terms, such as the terms "outer side", "middle section", "inner", "outer", etc., indicating the orientation and positional relationship are based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and should not be construed as limiting the specific protection scope of the present invention.

[0037] In addition, terms such as "first" and "second" are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, the meanings of "several" and "a number of" are two or more, unless otherwise specifically defined.

[0038] Referring Figure 4 and Figure 5 , an embodiment of the present invention provides an adaptive buck-boost drive circuit, which includes a main control, a Boost circuit, a load, a first switching transistor Q1' and a first diode D1'.

[0039] In the basic topology of a traditional Boost circuit, the main control is connected to the switching transistor in the Boost circuit to control the turn-off or turn-on of the switching transistor in the Boost circuit. The positive pole of the load is connected to the positive output terminal of the Boost circuit, and the negative pole of the load is grounded. In the present invention, the positive pole of the load is connected to the positive output terminal of the Boost circuit, while the negative pole of the load is not grounded to achieve automatic switching between the boost state and the buck-boost state of the entire circuit.

[0040] In existing drive circuits, an MCU main control is usually used to control the Boost circuit. The main control of the present invention shares this MCU main control to achieve the automatic switching function between the boost state and the buck-boost state without increasing the circuit cost.

[0041] The drain of the first switching transistor Q1' is connected to the negative pole of the load, the source of the first switching transistor Q1' is grounded, and the gate of the first switching transistor Q1' is connected to the main control. The positive pole of the first diode D1' is connected to the drain of the first switching transistor Q1', and the negative pole of the first diode D1' is connected to the power supply terminal Vin of the Boost circuit.

[0042] The present invention adds a first switching transistor Q1' and a first diode D1' to the traditional Boost circuit. When the first switching transistor Q1' is controlled to turn on, the first diode D1' bears a reverse voltage and is cut off. At this time, the Boost circuit operates in the boost state; when the first switching transistor Q1' is controlled to turn off, the Boost circuit operates in the buck-boost state, and the current of the load flows to the power supply terminal Vin through the first diode D1'.

[0043] In some embodiments, the first switching transistor Q1' is an NMOS transistor.

[0044] In some embodiments, the first switching transistor Q1' is an enhancement-mode NMOS transistor.

[0045] In some embodiments, the load is an LED lamp.

[0046] As Figure 4 and Figure 5 shown, the positive electrode of the LED lamp is connected to the positive output terminal of the Boost circuit, and the negative electrode of the LED lamp is connected to the drain of the first switching transistor Q1'.

[0047] In this embodiment, when the first switching transistor Q1' is controlled to conduct, the first diode D1' bears a reverse voltage and is cut off. At this time, the Boost circuit operates in a boost state, suitable for driving an LED lamp with more than 6 strings of lamp beads; when the first switching transistor Q1' is controlled to turn off, the Boost circuit operates in a buck-boost state, and the current of the LED lamp flows to the power supply terminal Vin through the first diode D1', suitable for driving an LED lamp with less than 6 strings of lamp beads.

[0048] Of course, the load of the present invention can also be other loads that need to achieve the automatic switching requirement between the boost state and the buck-boost state.

[0049] In some embodiments, the adaptive buck-boost drive circuit further includes a voltage acquisition circuit, which is used to acquire the voltage at the positive terminal of the load, and the output terminal of the voltage acquisition circuit is connected to the main control.

[0050] The voltage acquisition circuit in this embodiment can directly adopt any circuit in the prior art that can achieve voltage acquisition. For example, the voltage at the positive terminal of the load is acquired by using a sampling resistor method.

[0051] The output terminal of the voltage acquisition circuit is connected to the ADC sampling terminal of the main control, and the main control can obtain the voltage value at the positive terminal of the load.

[0052] In some embodiments, referring to Figure 3 and Figure 4 , the Boost circuit 1 is a boost-type Boost circuit, and the Boost circuit 1 includes a storage inductor L', a second diode D2', a filter capacitor C' and a second switching transistor Q2'.

[0053] One end of the storage inductor L' is connected to the power supply terminal Vin, and the other end of the storage inductor L' is respectively connected to the drain of the second switching transistor Q2' and the positive electrode of the second diode D2'.

[0054] The positive electrode of the second diode D2' is respectively connected to the other end of the storage inductor L' and the drain of the second switching transistor Q2', and the negative electrode of the second diode D2' is connected to the positive electrode of the load. That is to say, the negative terminal of the second diode D2' is the positive output terminal of the Boost circuit.

[0055] The positive electrode of the filter capacitor C' is connected to the negative electrode of the second diode D2', and the negative electrode of the filter capacitor C' is grounded.

[0056] The drain of the second switching transistor Q2' is respectively connected to the other end of the energy storage inductor L' and the anode of the second diode D2'. The source of the second switching transistor Q2' is grounded, and the gate of the second switching transistor Q2' is connected to the main control, and the main control controls the turn-off or turn-on of the second switching transistor Q2'.

[0057] The working principle of the Boost circuit 1 is as follows: When the second switching transistor Q2' is controlled to be turned on, the second diode D2' is turned off, and the voltage input from the power supply terminal Vin directly returns after passing through the energy storage inductor L', resulting in a linearly increasing current passing through the energy storage inductor L'. At this time, the filter capacitor C' discharges to the load. When the second switching transistor Q2' is controlled to be turned off, since the current in the energy storage inductor L' cannot change instantaneously, a reverse electromotive force Vl will be generated on the energy storage inductor L' to maintain the passing current unchanged. At this time, the second diode D2' is turned on, and the voltage (Vin + Vl) exceeding the voltage input from the power supply terminal Vin supplies power to the load and charges the filter capacitor C'. At this time, the Boost circuit 1 is in a step-up state.

[0058] In this embodiment, the Boost circuit 1 is a basic circuit structure. Of course, other boost-type Boost circuits based on Figure 3 this basic circuit deformation structure are applicable to the present invention.

[0059] For example, referring to Figure 5 , it is the application of the present invention in a two-phase interleaved Boost circuit, which is a deformation structure of the Boost circuit 1 based on Figure 3 . Compared with the Boost circuit 1 of Figure 3 , in addition to the energy storage inductor L', the second diode D2', the filter capacitor C' and the second switching transistor Q2' of the Boost circuit 1, the two-phase interleaved Boost circuit is additionally provided with a third energy storage inductor L3', a third diode D3' and a third switching transistor Q3'. The circuit connection methods of each component are the same as those of the energy storage inductor L', the second diode D2' and the second switching transistor Q2' of the Boost circuit 1, that is:

[0060] One end of the third energy storage inductor L3' is connected to the power supply terminal Vin, and the other end of the third energy storage inductor L3' is respectively connected to the drain of the third switching transistor Q3' and the anode of the third diode D3'.

[0061] The anode of the third diode D3' is respectively connected to the other end of the third energy storage inductor L3' and the drain of the third switching transistor Q3'. The cathode of the third diode D3' is connected to the positive pole of the load. That is to say, the negative terminal of the third diode D3' is also the positive output terminal of the two-phase interleaved Boost circuit.

[0062] The positive pole of the filter capacitor C' is connected to the cathode of the third diode D3', and the negative pole of the filter capacitor C' is grounded.

[0063] The drain of the third switching transistor Q3' is respectively connected to the other end of the third energy storage inductor L3' and the anode of the third diode D3'. The source of the third switching transistor Q3' is grounded, and the gate of the third switching transistor Q3' is connected to the main control, and the main control controls the turn-off or turn-on of the third switching transistor Q3'.

[0064] The embodiment of the present invention also provides an adaptive buck-boost driving method, which is used to drive the adaptive buck-boost driving circuit provided in each of the above embodiments of the present invention. The adaptive buck-boost driving method includes:

[0065] After power-on, the main control controls the first switching transistor Q1' to turn off, so that the adaptive buck-boost driving circuit operates in the buck-boost state. The main control collects the voltage value at the positive terminal of the load. If the voltage value is greater than the preset value, it controls the first switching transistor Q1' to turn on, so that the adaptive buck-boost driving circuit operates in the boost state. If the voltage value is not greater than the preset value, it keeps the first switching transistor Q1' in the off state.

[0066] The driving method of the present invention can perform a voltage value acquisition and judgment operation after each power-on, so as to make an adaptive adjustment according to the connected load conditions.

[0067] The preset value in the present invention can be set to different preset values according to different connected loads.

[0068] In some embodiments, the preset value is:

[0069] 2Vin + N

[0070] Wherein, Vin is the voltage value input at the power supply terminal of the Boost circuit, and N is a preset driving switching voltage value.

[0071] In this embodiment, N needs to satisfy not less than the voltage value by which the output voltage is higher than the input voltage, that is, N is greater than or equal to the voltage difference between the output voltage and the input voltage. Therefore, the driving switching voltage value is determined according to the connected load conditions, and it can be a preset natural number or decimal.

[0072] In some embodiments, when the load is an LED lamp, N ≥ 6V.

[0073] In this embodiment, when applied to automotive lamps, the voltage of the LED lamp is usually 3V, and the voltage value Vin at the input power supply terminal is usually 12V. Taking 6 series of LED lamps as the boundary, 6 series of LED lamps are 18V, which is 6V higher than the input voltage of 12V. Therefore, N is set to not less than 6V, and when the boost condition is met, the circuit can operate in the boost state.

[0074] An embodiment of the present invention also provides an automotive lamp, and the automotive lamp is provided with the adaptive buck-boost drive circuit provided in each of the above embodiments of the present invention.

[0075] Embodiment 1:

[0076] The adaptive buck-boost drive circuit is used to drive the automotive lamp, and the automotive lamp is connected as a load to the adaptive buck-boost drive circuit. Specifically, referring to Figure 4 , connect the positive electrode of the automotive lamp to LED+, and connect the negative electrode of the automotive lamp to LED-. The wiring is simple.

[0077] A MCU master is usually included in the drive board of the automotive lamp, and the adaptive buck-boost drive circuit can directly share this MCU master without increasing the circuit cost.

[0078] After power-on, the MCU master controls the first switching transistor Q1' to turn off. The control of the Boost circuit, especially the control of the second switching transistor Q2', adopts the prior art to make the whole circuit work in the buck-boost state.

[0079] The voltage V(LED+) at the LED+ terminal is collected by the ADC of the MCU master. If the number of LED strings is relatively large and satisfies V(LED+)-Vin>Vin+6, that is, V(LED+)>2Vin+6, the MCU master is made to control the first switching transistor Q1' to turn on, and the control of the Boost circuit adopts the prior art to make the whole circuit work in the boost state. At this time, the efficiency of the whole circuit will be improved; if the number of LED strings is relatively small and satisfies V(LED+)≤2Vin+6, keep the MOS transistor Q2 in the off state.

[0080] Among them, the control of the Boost circuit can adopt the prior art such as peak current mode control and / or voltage mode control, etc.

[0081] The present invention has been described in detail with reference to the embodiments with the accompanying drawings. Those of ordinary skill in the art can make various variations of the present invention according to the above description. Therefore, some details in the embodiments should not constitute a limitation to the present invention, and the present invention will take the scope defined by the appended claims as the protection scope.

Claims

1. An adaptive buck-boost driving circuit, comprising a main control, a Boost circuit and a load, characterized in that: The positive electrode of the load is connected to the positive output terminal of the Boost circuit; The adaptive buck-boost driving circuit further includes: A first switch tube, wherein a drain of the first switch tube is connected to a negative electrode of the load, a source of the first switch tube is grounded, and a gate of the first switch tube is connected to the main control; a first diode, wherein an anode of the first diode is connected to a drain of the first switch tube, and a cathode of the first diode is connected to a power supply terminal of the Boost circuit; After power-on, the main control controls the first switch tube to be turned off, so that the adaptive buck-boost driving circuit works in a buck-boost state; The main control collects the positive terminal voltage value of the load. If the voltage value is greater than a preset value, the first switch tube is controlled to be turned on so that the adaptive buck-boost drive circuit operates in a boost state. If the voltage value is not greater than the preset value, the first switch tube is kept in an off state.

2. The adaptive buck-boost driving circuit according to claim 1, characterized in that: The first switch tube is an NMOS tube.

3. The adaptive buck-boost driving circuit according to claim 2, characterized in that: The first switch tube is an enhanced NMOS tube.

4. The adaptive buck-boost driving circuit according to claim 1, wherein: The load is an LED lamp.

5. The adaptive buck-boost driving circuit according to claim 1, characterized in that: The adaptive buck-boost driving circuit further includes: A voltage acquisition circuit is configured to acquire the voltage at the positive terminal of the load, and the output end of the voltage acquisition circuit is connected to the main control.

6. The adaptive buck-boost driving circuit according to claim 1, characterized in that: The Boost circuit comprises: An energy storage inductor, one end of which is connected to the power supply end; a second diode, wherein a cathode of the second diode is connected to an anode of the load; A filter capacitor, wherein the positive electrode of the filter capacitor is connected to the negative electrode of the second diode, and the negative electrode of the filter capacitor is grounded; A second switch tube, wherein the drain of the second switch tube is respectively connected to the other end of the energy storage inductor and the anode of the second diode, the source of the second switch tube is grounded, and the gate of the second switch tube is connected to the main control.

7. The adaptive buck-boost driving circuit according to claim 1, characterized in that: The preset values ​​are: 2Vin+N Wherein, Vin is the voltage input to the power supply end of the Boost circuit, and N is a preset driving switching voltage value.

8. The adaptive buck-boost driving circuit according to claim 7, characterized in that: When the load is an LED lamp, N≥6V.

9. An automobile lamp, characterized in that: The automobile lamp has the adaptive buck-boost driving circuit according to any one of claims 1 to 8.

Images